There are a number of ways to interconnect signals from one electronic device to another. One method routes the signals through a package substrate of one device to a socket, onto a printed circuit board (PCB), and to another device, which may also be mounted on a package substrate and electrically coupled to the PCB through a socket. However, signals along such a path are susceptible to signal degradation and losses due to various parasitic mechanisms, transmission and return losses, and cross talk. The signal degradation and losses may be especially pronounced for high speed signals. Transmission losses may be reduced, for example, by constructing the PCB with materials having improved dielectric characteristics. However, significant degradation and losses may still be occur for longer interconnect paths and at higher signaling rates. Another way to interconnect signals uses flex cable that is electrically coupled to substrate packages and avoids routing the signals through the PCB. The flex cable may include a dielectric (insulating) material and an electrically conductive material, and conventionally includes a row of traces separated from a ground plane (or ground traces) by a dielectric layer.